From 2e8cdab8bc5c4b59d53aea407635c9a11a6cba69 Mon Sep 17 00:00:00 2001
From: jongleberry <me@jongleberry.com>
Date: Tue, 13 Oct 2015 17:45:18 -0700
Subject: [PATCH] support async functions

closes #530
closes #415
---
 Makefile                         |   3 +-
 benchmarks/Makefile              |  15 +--
 benchmarks/experimental/async.js |  28 -----
 benchmarks/experimental/index.js |   9 --
 lib/application.js               |  42 +++----
 package.json                     |   4 +-
 test/application/context.js      |  12 +-
 test/application/index.js        |  16 +--
 test/application/request.js      |  12 +-
 test/application/respond.js      | 210 +++++++++++++++----------------
 test/application/response.js     |  12 +-
 test/application/use.js          |  32 +++--
 test/context/cookies.js          |  18 +--
 test/context/onerror.js          |  26 ++--
 test/context/state.js            |   4 +-
 test/experimental/async.js       |  25 ----
 test/experimental/index.js       |   7 --
 test/request/href.js             |   4 +-
 test/response/attachment.js      |   6 +-
 test/response/body.js            |   4 +-
 test/response/status.js          |  30 ++---
 test/response/type.js            |   2 +-
 22 files changed, 217 insertions(+), 304 deletions(-)
 delete mode 100644 benchmarks/experimental/async.js
 delete mode 100644 benchmarks/experimental/index.js
 delete mode 100644 test/experimental/async.js
 delete mode 100644 test/experimental/index.js

diff --git a/Makefile b/Makefile
index a65b8da..a0c97bc 100644
--- a/Makefile
+++ b/Makefile
@@ -5,8 +5,7 @@ REQUIRED = --require should --require should-http
 TESTS = test/application/* \
 	test/context/* \
 	test/request/* \
-	test/response/* \
-	test/experimental/index.js
+	test/response/*
 
 lint:
 	@./node_modules/.bin/eslint lib test
diff --git a/benchmarks/Makefile b/benchmarks/Makefile
index 46d0690..7faa410 100644
--- a/benchmarks/Makefile
+++ b/benchmarks/Makefile
@@ -1,5 +1,5 @@
 
-all: middleware experimental
+all: middleware
 
 middleware:
 	@./run 1 $@
@@ -12,15 +12,4 @@ middleware:
 	@./run 100 $@
 	@echo
 
-experimental:
-	@./run 1 $@
-	@./run 5 $@
-	@./run 10 $@
-	@./run 15 $@
-	@./run 20 $@
-	@./run 30 $@
-	@./run 50 $@
-	@./run 100 $@
-	@echo
-
-.PHONY: all middleware experimental
+.PHONY: all middleware
diff --git a/benchmarks/experimental/async.js b/benchmarks/experimental/async.js
deleted file mode 100644
index 757e3eb..0000000
--- a/benchmarks/experimental/async.js
+++ /dev/null
@@ -1,28 +0,0 @@
-
-'use strict';
-
-const http = require('http');
-const Koa = require('../..');
-const app = new Koa();
-
-app.experimental = true;
-
-// number of middleware
-
-let n = parseInt(process.env.MW || '1', 10);
-console.log(`  ${n} async middleware`);
-
-while (n--) {
-  app.use(async function (next){
-    await next;
-  });
-}
-
-const body = new Buffer('Hello World');
-
-app.use(async function (next){
-  await next;
-  this.body = body;
-});
-
-app.listen(3333);
diff --git a/benchmarks/experimental/index.js b/benchmarks/experimental/index.js
deleted file mode 100644
index 5c39caf..0000000
--- a/benchmarks/experimental/index.js
+++ /dev/null
@@ -1,9 +0,0 @@
-
-'use strict';
-
-// support async await by babel
-require('babel/register')({
-  optional: ['asyncToGenerator']
-});
-
-require('./async');
diff --git a/lib/application.js b/lib/application.js
index cd293e9..833b582 100644
--- a/lib/application.js
+++ b/lib/application.js
@@ -5,9 +5,9 @@
  * Module dependencies.
  */
 
+const isGeneratorFunction = require('is-generator-function');
 const debug = require('debug')('koa:application');
 const Emitter = require('events').EventEmitter;
-const compose_es7 = require('composition');
 const onFinished = require('on-finished');
 const response = require('./response');
 const compose = require('koa-compose');
@@ -91,11 +91,9 @@ module.exports = class Application extends Emitter {
    */
 
   use(fn) {
-    if (!this.experimental) {
-      // es7 async functions are allowed
-      assert(fn && 'GeneratorFunction' == fn.constructor.name, 'app.use() requires a generator function');
-    }
     debug('use %s', fn._name || fn.name || '-');
+    if (typeof fn !== 'function') throw new TypeError('middleware must be a function!');
+    if (isGeneratorFunction(fn)) fn = co.wrap(fn);
     this.middleware.push(fn);
     return this;
   }
@@ -109,9 +107,7 @@ module.exports = class Application extends Emitter {
    */
 
   callback() {
-    const fn = this.experimental
-      ? compose_es7(this.middleware)
-      : co.wrap(compose(this.middleware));
+    const fn = compose(this.middleware);
 
     if (!this.listeners('error').length) this.on('error', this.onerror);
 
@@ -119,8 +115,8 @@ module.exports = class Application extends Emitter {
       res.statusCode = 404;
       const ctx = this.createContext(req, res);
       onFinished(res, ctx.onerror);
-      fn.call(ctx).then(function() {
-        respond.call(ctx);
+      fn(ctx).then(function() {
+        respond(ctx);
       }).catch(ctx.onerror);
     };
   }
@@ -176,33 +172,33 @@ module.exports = class Application extends Emitter {
  * Response helper.
  */
 
-function respond() {
+function respond(ctx) {
   // allow bypassing koa
-  if (false === this.respond) return;
+  if (false === ctx.respond) return;
 
-  const res = this.res;
-  if (res.headersSent || !this.writable) return;
+  const res = ctx.res;
+  if (res.headersSent || !ctx.writable) return;
 
-  let body = this.body;
-  const code = this.status;
+  let body = ctx.body;
+  const code = ctx.status;
 
   // ignore body
   if (statuses.empty[code]) {
     // strip headers
-    this.body = null;
+    ctx.body = null;
     return res.end();
   }
 
-  if ('HEAD' == this.method) {
-    if (isJSON(body)) this.length = Buffer.byteLength(JSON.stringify(body));
+  if ('HEAD' == ctx.method) {
+    if (isJSON(body)) ctx.length = Buffer.byteLength(JSON.stringify(body));
     return res.end();
   }
 
   // status body
   if (null == body) {
-    this.type = 'text';
-    body = this.message || String(code);
-    this.length = Buffer.byteLength(body);
+    ctx.type = 'text';
+    body = ctx.message || String(code);
+    ctx.length = Buffer.byteLength(body);
     return res.end(body);
   }
 
@@ -213,6 +209,6 @@ function respond() {
 
   // body: json
   body = JSON.stringify(body);
-  this.length = Buffer.byteLength(body);
+  ctx.length = Buffer.byteLength(body);
   res.end(body);
 }
diff --git a/package.json b/package.json
index e488747..1d19023 100644
--- a/package.json
+++ b/package.json
@@ -20,7 +20,6 @@
   "dependencies": {
     "accepts": "^1.2.2",
     "co": "^4.4.0",
-    "composition": "^2.1.1",
     "content-disposition": "~0.5.0",
     "content-type": "^1.0.0",
     "cookies": "~0.5.0",
@@ -32,7 +31,8 @@
     "fresh": "^0.3.0",
     "http-assert": "^1.1.0",
     "http-errors": "^1.2.8",
-    "koa-compose": "^2.3.0",
+    "is-generator-function": "^1.0.3",
+    "koa-compose": "^3.0.0",
     "koa-is-json": "^1.0.0",
     "mime-types": "^2.0.7",
     "on-finished": "^2.1.0",
diff --git a/test/application/context.js b/test/application/context.js
index 6446d77..718c148 100644
--- a/test/application/context.js
+++ b/test/application/context.js
@@ -11,9 +11,9 @@ describe('app.context', function(){
   const app2 = new Koa();
 
   it('should merge properties', function(done){
-    app1.use(function *(next){
-      assert.equal(this.msg, 'hello');
-      this.status = 204;
+    app1.use(function *(ctx, next){
+      assert.equal(ctx.msg, 'hello');
+      ctx.status = 204;
     });
 
     request(app1.listen())
@@ -22,9 +22,9 @@ describe('app.context', function(){
   });
 
   it('should not affect the original prototype', function(done){
-    app2.use(function *(next){
-      assert.equal(this.msg, undefined);
-      this.status = 204;
+    app2.use(function *(ctx, next){
+      assert.equal(ctx.msg, undefined);
+      ctx.status = 204;
     });
 
     request(app2.listen())
diff --git a/test/application/index.js b/test/application/index.js
index f961b95..9dd7e5c 100644
--- a/test/application/index.js
+++ b/test/application/index.js
@@ -9,9 +9,9 @@ describe('app', function(){
   it('should handle socket errors', function(done){
     const app = new Koa();
 
-    app.use(function *(next){
-      // triggers this.socket.writable == false
-      this.socket.emit('error', new Error('boom'));
+    app.use(function *(ctx, next){
+      // triggers ctx.socket.writable == false
+      ctx.socket.emit('error', new Error('boom'));
     });
 
     app.on('error', function(err){
@@ -27,13 +27,13 @@ describe('app', function(){
   it('should not .writeHead when !socket.writable', function(done){
     const app = new Koa();
 
-    app.use(function *(next){
+    app.use(function *(ctx, next){
       // set .writable to false
-      this.socket.writable = false;
-      this.status = 204;
+      ctx.socket.writable = false;
+      ctx.status = 204;
       // throw if .writeHead or .end is called
-      this.res.writeHead =
-      this.res.end = function(){
+      ctx.res.writeHead =
+      ctx.res.end = function(){
         throw new Error('response sent');
       };
     });
diff --git a/test/application/request.js b/test/application/request.js
index 0dd8599..3050127 100644
--- a/test/application/request.js
+++ b/test/application/request.js
@@ -11,9 +11,9 @@ describe('app.request', function(){
   const app2 = new Koa();
 
   it('should merge properties', function(done){
-    app1.use(function *(next){
-      assert.equal(this.request.message, 'hello');
-      this.status = 204;
+    app1.use(function *(ctx, next){
+      assert.equal(ctx.request.message, 'hello');
+      ctx.status = 204;
     });
 
     request(app1.listen())
@@ -22,9 +22,9 @@ describe('app.request', function(){
   });
 
   it('should not affect the original prototype', function(done){
-    app2.use(function *(next){
-      assert.equal(this.request.message, undefined);
-      this.status = 204;
+    app2.use(function *(ctx, next){
+      assert.equal(ctx.request.message, undefined);
+      ctx.status = 204;
     });
 
     request(app2.listen())
diff --git a/test/application/respond.js b/test/application/respond.js
index 2cc3987..42779a1 100644
--- a/test/application/respond.js
+++ b/test/application/respond.js
@@ -8,15 +8,15 @@ const Koa = require('../..');
 const fs = require('fs');
 
 describe('app.respond', function(){
-  describe('when this.respond === false', function(){
-    it('should bypass app.respond', function(done){
+  describe('when ctx.respond === false', function(){
+    it('should function *(ctx)', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = 'Hello';
-        this.respond = false;
+      app.use(function *(ctx){
+        ctx.body = 'Hello';
+        ctx.respond = false;
 
-        const res = this.res;
+        const res = ctx.res;
         res.statusCode = 200;
         setImmediate(function(){
           res.setHeader('Content-Type', 'text/plain');
@@ -38,9 +38,9 @@ describe('app.respond', function(){
     it('should not send Content-Type header', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = '';
-        this.type = null;
+      app.use(function *(ctx){
+        ctx.body = '';
+        ctx.type = null;
       });
 
       const server = app.listen();
@@ -60,8 +60,8 @@ describe('app.respond', function(){
     it('should not respond with the body', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = 'Hello';
+      app.use(function *(ctx){
+        ctx.body = 'Hello';
       });
 
       const server = app.listen();
@@ -81,8 +81,8 @@ describe('app.respond', function(){
     it('should keep json headers', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = { hello: 'world' };
+      app.use(function *(ctx){
+        ctx.body = { hello: 'world' };
       });
 
       const server = app.listen();
@@ -102,8 +102,8 @@ describe('app.respond', function(){
     it('should keep string headers', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = 'hello world';
+      app.use(function *(ctx){
+        ctx.body = 'hello world';
       });
 
       const server = app.listen();
@@ -123,8 +123,8 @@ describe('app.respond', function(){
     it('should keep buffer headers', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = new Buffer('hello world');
+      app.use(function *(ctx){
+        ctx.body = new Buffer('hello world');
       });
 
       const server = app.listen();
@@ -144,7 +144,7 @@ describe('app.respond', function(){
     it('should respond with a 404 if no body was set', function(done){
       const app = new Koa();
 
-      app.use(function *(){
+      app.use(function *(ctx){
 
       });
 
@@ -158,8 +158,8 @@ describe('app.respond', function(){
     it('should respond with a 200 if body = ""', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = '';
+      app.use(function *(ctx){
+        ctx.body = '';
       });
 
       const server = app.listen();
@@ -172,9 +172,9 @@ describe('app.respond', function(){
     it('should not overwrite the content-type', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.status = 200;
-        this.type = 'application/javascript';
+      app.use(function *(ctx){
+        ctx.status = 200;
+        ctx.type = 'application/javascript';
       });
 
       const server = app.listen();
@@ -202,9 +202,9 @@ describe('app.respond', function(){
     it('should not cause an app error', function(done){
       const app = new Koa();
 
-      app.use(function *(next){
-        const res = this.res;
-        this.status = 200;
+      app.use(function *(ctx, next){
+        const res = ctx.res;
+        ctx.status = 200;
         res.setHeader('Content-Type', 'text/html');
         res.write('Hello');
         setTimeout(function(){
@@ -233,9 +233,9 @@ describe('app.respond', function(){
     it('should send the right body', function(done){
       const app = new Koa();
 
-      app.use(function *(next){
-        const res = this.res;
-        this.status = 200;
+      app.use(function *(ctx, next){
+        const res = ctx.res;
+        ctx.status = 200;
         res.setHeader('Content-Type', 'text/html');
         res.write('Hello');
         setTimeout(function(){
@@ -257,8 +257,8 @@ describe('app.respond', function(){
       it('should respond with the associated status message', function(done){
         const app = new Koa();
 
-        app.use(function *(){
-          this.status = 400;
+        app.use(function *(ctx){
+          ctx.status = 400;
         });
 
         const server = app.listen();
@@ -275,8 +275,8 @@ describe('app.respond', function(){
       it('should respond without a body', function(done){
         const app = new Koa();
 
-        app.use(function *(){
-          this.status = 204;
+        app.use(function *(ctx){
+          ctx.status = 204;
         });
 
         const server = app.listen();
@@ -298,8 +298,8 @@ describe('app.respond', function(){
       it('should respond without a body', function(done){
         const app = new Koa();
 
-        app.use(function *(){
-          this.status = 205;
+        app.use(function *(ctx){
+          ctx.status = 205;
         });
 
         const server = app.listen();
@@ -321,8 +321,8 @@ describe('app.respond', function(){
       it('should respond without a body', function(done){
         const app = new Koa();
 
-        app.use(function *(){
-          this.status = 304;
+        app.use(function *(ctx){
+          ctx.status = 304;
         });
 
         const server = app.listen();
@@ -345,8 +345,8 @@ describe('app.respond', function(){
         const app = new Koa();
         statuses['700'] = 'custom status';
 
-        app.use(function *(){
-          this.status = 700;
+        app.use(function *(ctx){
+          ctx.status = 700;
         });
 
         const server = app.listen();
@@ -367,9 +367,9 @@ describe('app.respond', function(){
       it('should respond with the custom status message', function(done){
         const app = new Koa();
 
-        app.use(function *(){
-          this.status = 200;
-          this.message = 'ok';
+        app.use(function *(ctx){
+          ctx.status = 200;
+          ctx.message = 'ok';
         });
 
         const server = app.listen();
@@ -390,8 +390,8 @@ describe('app.respond', function(){
       it('should respond with the status code number', function(done){
         const app = new Koa();
 
-        app.use(function *(){
-          this.res.statusCode = 701;
+        app.use(function *(ctx){
+          ctx.res.statusCode = 701;
         });
 
         const server = app.listen();
@@ -408,8 +408,8 @@ describe('app.respond', function(){
     it('should respond 204 by default', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = null;
+      app.use(function *(ctx){
+        ctx.body = null;
       });
 
       const server = app.listen();
@@ -429,9 +429,9 @@ describe('app.respond', function(){
     it('should respond 204 with status=200', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.status = 200;
-        this.body = null;
+      app.use(function *(ctx){
+        ctx.status = 200;
+        ctx.body = null;
       });
 
       const server = app.listen();
@@ -451,9 +451,9 @@ describe('app.respond', function(){
     it('should respond 205 with status=205', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.status = 205;
-        this.body = null;
+      app.use(function *(ctx){
+        ctx.status = 205;
+        ctx.body = null;
       });
 
       const server = app.listen();
@@ -473,9 +473,9 @@ describe('app.respond', function(){
     it('should respond 304 with status=304', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.status = 304;
-        this.body = null;
+      app.use(function *(ctx){
+        ctx.status = 304;
+        ctx.body = null;
       });
 
       const server = app.listen();
@@ -497,8 +497,8 @@ describe('app.respond', function(){
     it('should respond', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = 'Hello';
+      app.use(function *(ctx){
+        ctx.body = 'Hello';
       });
 
       const server = app.listen();
@@ -513,8 +513,8 @@ describe('app.respond', function(){
     it('should respond', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = new Buffer('Hello');
+      app.use(function *(ctx){
+        ctx.body = new Buffer('Hello');
       });
 
       const server = app.listen();
@@ -529,9 +529,9 @@ describe('app.respond', function(){
     it('should respond', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = fs.createReadStream('package.json');
-        this.set('Content-Type', 'application/json; charset=utf-8');
+      app.use(function *(ctx){
+        ctx.body = fs.createReadStream('package.json');
+        ctx.set('Content-Type', 'application/json; charset=utf-8');
       });
 
       const server = app.listen();
@@ -551,10 +551,10 @@ describe('app.respond', function(){
     it('should strip content-length when overwriting', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = 'hello';
-        this.body = fs.createReadStream('package.json');
-        this.set('Content-Type', 'application/json; charset=utf-8');
+      app.use(function *(ctx){
+        ctx.body = 'hello';
+        ctx.body = fs.createReadStream('package.json');
+        ctx.set('Content-Type', 'application/json; charset=utf-8');
       });
 
       const server = app.listen();
@@ -574,10 +574,10 @@ describe('app.respond', function(){
     it('should keep content-length if not overwritten', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.length = fs.readFileSync('package.json').length;
-        this.body = fs.createReadStream('package.json');
-        this.set('Content-Type', 'application/json; charset=utf-8');
+      app.use(function *(ctx){
+        ctx.length = fs.readFileSync('package.json').length;
+        ctx.body = fs.createReadStream('package.json');
+        ctx.set('Content-Type', 'application/json; charset=utf-8');
       });
 
       const server = app.listen();
@@ -597,12 +597,12 @@ describe('app.respond', function(){
     it('should keep content-length if overwritten with the same stream', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.length = fs.readFileSync('package.json').length;
+      app.use(function *(ctx){
+        ctx.length = fs.readFileSync('package.json').length;
         const stream = fs.createReadStream('package.json');
-        this.body = stream;
-        this.body = stream;
-        this.set('Content-Type', 'application/json; charset=utf-8');
+        ctx.body = stream;
+        ctx.body = stream;
+        ctx.set('Content-Type', 'application/json; charset=utf-8');
       });
 
       const server = app.listen();
@@ -622,9 +622,9 @@ describe('app.respond', function(){
     it('should handle errors', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.set('Content-Type', 'application/json; charset=utf-8');
-        this.body = fs.createReadStream('does not exist');
+      app.use(function *(ctx){
+        ctx.set('Content-Type', 'application/json; charset=utf-8');
+        ctx.body = fs.createReadStream('does not exist');
       });
 
       const server = app.listen();
@@ -639,9 +639,9 @@ describe('app.respond', function(){
     it('should handle errors when no content status', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.status = 204;
-        this.body = fs.createReadStream('does not exist');
+      app.use(function *(ctx){
+        ctx.status = 204;
+        ctx.body = fs.createReadStream('does not exist');
       });
 
       const server = app.listen();
@@ -654,10 +654,10 @@ describe('app.respond', function(){
     it('should handle all intermediate stream body errors', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = fs.createReadStream('does not exist');
-        this.body = fs.createReadStream('does not exist');
-        this.body = fs.createReadStream('does not exist');
+      app.use(function *(ctx){
+        ctx.body = fs.createReadStream('does not exist');
+        ctx.body = fs.createReadStream('does not exist');
+        ctx.body = fs.createReadStream('does not exist');
       });
 
       const server = app.listen();
@@ -672,8 +672,8 @@ describe('app.respond', function(){
     it('should respond with json', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = { hello: 'world' };
+      app.use(function *(ctx){
+        ctx.body = { hello: 'world' };
       });
 
       const server = app.listen();
@@ -689,7 +689,7 @@ describe('app.respond', function(){
     it('should emit "error" on the app', function(done){
       const app = new Koa();
 
-      app.use(function *(){
+      app.use(function *(ctx){
         throw new Error('boom');
       });
 
@@ -707,7 +707,7 @@ describe('app.respond', function(){
       it('should expose the message', function(done){
         const app = new Koa();
 
-        app.use(function *(){
+        app.use(function *(ctx){
           const err = new Error('sorry!');
           err.status = 403;
           err.expose = true;
@@ -725,7 +725,7 @@ describe('app.respond', function(){
       it('should respond with .status', function(done){
         const app = new Koa();
 
-        app.use(function *(){
+        app.use(function *(ctx){
           const err = new Error('s3 explodes');
           err.status = 403;
           throw err;
@@ -741,7 +741,7 @@ describe('app.respond', function(){
     it('should respond with 500', function(done){
       const app = new Koa();
 
-      app.use(function *(){
+      app.use(function *(ctx){
         throw new Error('boom!');
       });
 
@@ -756,16 +756,16 @@ describe('app.respond', function(){
     it('should be catchable', function(done){
       const app = new Koa();
 
-      app.use(function *(next){
+      app.use(function *(ctx, next){
         try {
-          yield next;
-          this.body = 'Hello';
+          yield next();
+          ctx.body = 'Hello';
         } catch (err) {
-          this.body = 'Got error';
+          ctx.body = 'Got error';
         }
       });
 
-      app.use(function *(next){
+      app.use(function *(ctx, next){
         throw new Error('boom!');
       });
 
@@ -782,10 +782,10 @@ describe('app.respond', function(){
     it('should 200', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.status = 304;
-        this.body = 'hello';
-        this.status = 200;
+      app.use(function *(ctx){
+        ctx.status = 304;
+        ctx.body = 'hello';
+        ctx.status = 200;
       });
 
       const server = app.listen();
@@ -799,11 +799,11 @@ describe('app.respond', function(){
     it('should 204', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.status = 200;
-        this.body = 'hello';
-        this.set('content-type', 'text/plain; charset=utf8');
-        this.status = 204;
+      app.use(function *(ctx){
+        ctx.status = 200;
+        ctx.body = 'hello';
+        ctx.set('content-type', 'text/plain; charset=utf8');
+        ctx.status = 204;
       });
 
       const server = app.listen();
diff --git a/test/application/response.js b/test/application/response.js
index f4840fb..e4e0d41 100644
--- a/test/application/response.js
+++ b/test/application/response.js
@@ -11,9 +11,9 @@ describe('app.response', function(){
   const app2 = new Koa();
 
   it('should merge properties', function(done){
-    app1.use(function *(next){
-      assert.equal(this.response.msg, 'hello');
-      this.status = 204;
+    app1.use(function *(ctx, next){
+      assert.equal(ctx.response.msg, 'hello');
+      ctx.status = 204;
     });
 
     request(app1.listen())
@@ -22,9 +22,9 @@ describe('app.response', function(){
   });
 
   it('should not affect the original prototype', function(done){
-    app2.use(function *(next){
-      assert.equal(this.response.msg, undefined);
-      this.status = 204;
+    app2.use(function *(ctx, next){
+      assert.equal(ctx.response.msg, undefined);
+      ctx.status = 204;
     });
 
     request(app2.listen())
diff --git a/test/application/use.js b/test/application/use.js
index ebf1eed..dcdefd7 100644
--- a/test/application/use.js
+++ b/test/application/use.js
@@ -9,21 +9,21 @@ describe('app.use(fn)', function(){
     const app = new Koa();
     const calls = [];
 
-    app.use(function *(next){
+    app.use(function *(ctx, next){
       calls.push(1);
-      yield next;
+      yield next();
       calls.push(6);
     });
 
-    app.use(function *(next){
+    app.use(function *(ctx, next){
       calls.push(2);
-      yield next;
+      yield next();
       calls.push(5);
     });
 
-    app.use(function *(next){
+    app.use(function *(ctx, next){
       calls.push(3);
-      yield next;
+      yield next();
       calls.push(4);
     });
 
@@ -39,19 +39,17 @@ describe('app.use(fn)', function(){
     });
   });
 
-  it('should error when a non-generator function is passed', function(){
+  // https://github.com/koajs/koa/pull/530#issuecomment-148138051
+  it('should catch thrown errors in non-async functions', function(done){
     const app = new Koa();
 
-    try {
-      app.use(function(){});
-    } catch (err) {
-      err.message.should.equal('app.use() requires a generator function');
-    }
-  });
+    app.use(ctx => {
+      ctx.throw('Not Found', 404);
+    });
 
-  it('should not error when a non-generator function is passed when .experimental=true', function(){
-    const app = new Koa();
-    app.experimental = true;
-    app.use(function(){});
+    request(app.listen())
+    .get('/')
+    .expect(404)
+    .end(done);
   });
 });
diff --git a/test/context/cookies.js b/test/context/cookies.js
index 0114e97..a3661fa 100644
--- a/test/context/cookies.js
+++ b/test/context/cookies.js
@@ -8,9 +8,9 @@ describe('ctx.cookies.set()', function(){
   it('should set an unsigned cookie', function(done){
     const app = new Koa();
 
-    app.use(function *(next){
-      this.cookies.set('name', 'jon');
-      this.status = 204;
+    app.use(function *(ctx, next){
+      ctx.cookies.set('name', 'jon');
+      ctx.status = 204;
     });
 
     const server = app.listen();
@@ -34,11 +34,11 @@ describe('ctx.cookies.set()', function(){
       it('should error', function(done){
         const app = new Koa();
 
-        app.use(function *(next){
+        app.use(function *(ctx, next){
           try {
-            this.cookies.set('foo', 'bar', { signed: true });
+            ctx.cookies.set('foo', 'bar', { signed: true });
           } catch (err) {
-            this.body = err.message;
+            ctx.body = err.message;
           }
         });
 
@@ -53,9 +53,9 @@ describe('ctx.cookies.set()', function(){
 
       app.keys = ['a', 'b'];
 
-      app.use(function *(next){
-        this.cookies.set('name', 'jon', { signed: true });
-        this.status = 204;
+      app.use(function *(ctx, next){
+        ctx.cookies.set('name', 'jon', { signed: true });
+        ctx.status = 204;
       });
 
       const server = app.listen();
diff --git a/test/context/onerror.js b/test/context/onerror.js
index 6f176dd..75b3171 100644
--- a/test/context/onerror.js
+++ b/test/context/onerror.js
@@ -8,10 +8,10 @@ describe('ctx.onerror(err)', function(){
   it('should respond', function(done){
     const app = new Koa();
 
-    app.use(function *(next){
-      this.body = 'something else';
+    app.use(function *(ctx, next){
+      ctx.body = 'something else';
 
-      this.throw(418, 'boom');
+      ctx.throw(418, 'boom');
     });
 
     const server = app.listen();
@@ -27,12 +27,12 @@ describe('ctx.onerror(err)', function(){
   it('should unset all headers', function(done){
     const app = new Koa();
 
-    app.use(function *(next){
-      this.set('Vary', 'Accept-Encoding');
-      this.set('X-CSRF-Token', 'asdf');
-      this.body = 'response';
+    app.use(function *(ctx, next){
+      ctx.set('Vary', 'Accept-Encoding');
+      ctx.set('X-CSRF-Token', 'asdf');
+      ctx.body = 'response';
 
-      this.throw(418, 'boom');
+      ctx.throw(418, 'boom');
     });
 
     const server = app.listen();
@@ -57,8 +57,8 @@ describe('ctx.onerror(err)', function(){
       it('should respond 500', function(done){
         const app = new Koa();
 
-        app.use(function *(next){
-          this.body = 'something else';
+        app.use(function *(ctx, next){
+          ctx.body = 'something else';
           const err = new Error('some error');
           err.status = 'notnumber';
           throw err;
@@ -78,8 +78,8 @@ describe('ctx.onerror(err)', function(){
       it('should respond 500', function(done){
         const app = new Koa();
 
-        app.use(function *(next){
-          this.body = 'something else';
+        app.use(function *(ctx, next){
+          ctx.body = 'something else';
           const err = new Error('some error');
           err.status = 9999;
           throw err;
@@ -100,7 +100,7 @@ describe('ctx.onerror(err)', function(){
     it('should response non-error thrown message', function(done){
       const app = new Koa();
 
-      app.use(function *(next){
+      app.use(function *(ctx, next){
         throw 'string error'; // eslint-disable-line no-throw-literal
       });
 
diff --git a/test/context/state.js b/test/context/state.js
index 1c80d63..7f316d3 100644
--- a/test/context/state.js
+++ b/test/context/state.js
@@ -9,8 +9,8 @@ describe('ctx.state', function(){
   it('should provide a ctx.state namespace', function(done){
     const app = new Koa();
 
-    app.use(function *(){
-      assert.deepEqual(this.state, {});
+    app.use(function *(ctx){
+      assert.deepEqual(ctx.state, {});
     });
 
     const server = app.listen();
diff --git a/test/experimental/async.js b/test/experimental/async.js
deleted file mode 100644
index 4eacdc5..0000000
--- a/test/experimental/async.js
+++ /dev/null
@@ -1,25 +0,0 @@
-
-'use strict';
-
-/**
- * Separate file primarily because we use `require('babel/register')`.
- */
-
-const request = require('supertest');
-const Koa = require('../..');
-
-describe('.experimental=true', function(){
-  it('should support async functions', function(done){
-    const app = new Koa();
-    app.experimental = true;
-    app.use(async function (next){
-      const string = await Promise.resolve('asdf');
-      this.body = string;
-    });
-
-    request(app.callback())
-    .get('/')
-    .expect('asdf')
-    .expect(200, done);
-  });
-});
diff --git a/test/experimental/index.js b/test/experimental/index.js
deleted file mode 100644
index bfe2862..0000000
--- a/test/experimental/index.js
+++ /dev/null
@@ -1,7 +0,0 @@
-
-'use strict';
-
-require('babel/register')({
-  optional: ['asyncToGenerator']
-});
-require('./async');
diff --git a/test/request/href.js b/test/request/href.js
index abff575..b9d018d 100644
--- a/test/request/href.js
+++ b/test/request/href.js
@@ -26,8 +26,8 @@ describe('ctx.href', function(){
 
   it('should work with `GET http://example.com/foo`', function(done){
     const app = new Koa();
-    app.use(function *(){
-      this.body = this.href;
+    app.use(function *(ctx){
+      ctx.body = ctx.href;
     });
     app.listen(function(){
       const address = this.address();
diff --git a/test/response/attachment.js b/test/response/attachment.js
index 2a1c5c9..7b73d2b 100644
--- a/test/response/attachment.js
+++ b/test/response/attachment.js
@@ -34,9 +34,9 @@ describe('ctx.attachment([filename])', function(){
     it('should work with http client', function(done){
       const app = new Koa();
 
-      app.use(function *(next){
-        this.attachment('path/to/include-no-ascii-char-中文名-ok.json');
-        this.body = {foo: 'bar'};
+      app.use(function *(ctx, next){
+        ctx.attachment('path/to/include-no-ascii-char-中文名-ok.json');
+        ctx.body = {foo: 'bar'};
       });
 
       request(app.listen())
diff --git a/test/response/body.js b/test/response/body.js
index f4ae66d..e630982 100644
--- a/test/response/body.js
+++ b/test/response/body.js
@@ -90,10 +90,10 @@ describe('res.body=', function(){
   describe('when an xml string is given', function(){
     it('should default to html', function(){
       /**
-       * This test is to show that we're not going
+       * ctx test is to show that we're not going
        * to be stricter with the html sniff
        * or that we will sniff other string types.
-       * You should `.type=` if this simple test fails.
+       * You should `.type=` if ctx simple test fails.
        */
 
       const res = response();
diff --git a/test/response/status.js b/test/response/status.js
index 14776b8..6900645 100644
--- a/test/response/status.js
+++ b/test/response/status.js
@@ -62,15 +62,15 @@ describe('res.status=', function(){
     it('should strip content related header fields', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.body = { foo: 'bar' };
-        this.set('Content-Type', 'application/json; charset=utf-8');
-        this.set('Content-Length', '15');
-        this.set('Transfer-Encoding', 'chunked');
-        this.status = status;
-        assert(null == this.response.header['content-type']);
-        assert(null == this.response.header['content-length']);
-        assert(null == this.response.header['transfer-encoding']);
+      app.use(function *(ctx){
+        ctx.body = { foo: 'bar' };
+        ctx.set('Content-Type', 'application/json; charset=utf-8');
+        ctx.set('Content-Length', '15');
+        ctx.set('Transfer-Encoding', 'chunked');
+        ctx.status = status;
+        assert(null == ctx.response.header['content-type']);
+        assert(null == ctx.response.header['content-length']);
+        assert(null == ctx.response.header['transfer-encoding']);
       });
 
       request(app.listen())
@@ -88,12 +88,12 @@ describe('res.status=', function(){
     it('should strip content releated header fields after status set', function(done){
       const app = new Koa();
 
-      app.use(function *(){
-        this.status = status;
-        this.body = { foo: 'bar' };
-        this.set('Content-Type', 'application/json; charset=utf-8');
-        this.set('Content-Length', '15');
-        this.set('Transfer-Encoding', 'chunked');
+      app.use(function *(ctx){
+        ctx.status = status;
+        ctx.body = { foo: 'bar' };
+        ctx.set('Content-Type', 'application/json; charset=utf-8');
+        ctx.set('Content-Length', '15');
+        ctx.set('Transfer-Encoding', 'chunked');
       });
 
       request(app.listen())
diff --git a/test/response/type.js b/test/response/type.js
index a748736..dc1e2a4 100644
--- a/test/response/type.js
+++ b/test/response/type.js
@@ -55,7 +55,7 @@ describe('ctx.type', function(){
   describe('with no Content-Type', function(){
     it('should return ""', function(){
       const ctx = context();
-      // TODO: this is lame
+      // TODO: ctx is lame
       assert('' === ctx.type);
     });
   });